Solutions to Nikoli Hurdles 2 – Part 4/5


Puzzle 6: Five Cells
From the inclusion of Five Cells, I learnt that the world needs more of them. I have been solving a lot of Five Cells in Nikoli magazines so I took it for granted that it was a well-known type. Imagine my surprise when I was showered with praise for this puzzle!

Adam Dewberry: Particularly enjoyed number 6  🙂

Rakesh Rai: I liked the sixth puzzle (five cells) the most, perhaps because it was new for me.

John Reid: Five Cells was also very entertaining for me as I don’t think I’ve seen that type before.

In a usual Nikoli magazine, Five Cells are scattered with 0’s. Even the hard ones are littered with 0’s. That’s an instant X-pentomino wherever you see a 0. If that’s not easy enough; how about a generous amount of 3s all around the perimeter?
Seriously, Nikoli?

So I came up with one without 0s and a lot less clues around the border. The middle of the puzzle is where all the challenge is at. Although, I don’t think it was that tough given how quickly you can try twisting the pieces in your head and fixing trial and errors.

5cellsanswerPuzzle 7: Kurodoko
This puzzle was written in a hotel way back in March, I remember this because it was written in my grid-squared diary. When I came round to edit the puzzle it broke no less than three times. According to my own test solving, this was the hardest puzzle in Nikoli Hurdles 2. The theme I was trying to work on was that each trio of clues sums up to 10. We have 8+2=10, 7+3=10, 6+4=10 and a scattered 5+5=10.


The puzzle revolves around the centre’s 10 diagonally adjacent to the 2. There are two possible configurations but one will only work when you consider the 5s at the bottom. I felt that during a timed competition, guess-and-check beats logic in this particular puzzle.



Solutions to Nikoli Hurdles 2 – Part 3/5


Puzzle 5: Select Words
A word puzzle!
As with all surprises; it can either mean a pleasant one or a bad surprise. If you are a purely logic puzzle fan expecting a run of nothing but logic puzzles, your reaction might be getting slapped in the face with a word puzzle. Otherwise, Select Words might come as a nice little gift before Christmas. If you can overcome the intimidating factor of the unexpectedness, you might find that the puzzle wasn’t that hard after all, as solver Alan O’Donnell indicated, “Round 5 was a little out of character though – non-logical is ok, but it was trivially easy.”

And it had to be easy. A lot of my audience does not primarily use English, including Matej Uher, “the hardest puzzle, at least for me, was obviously Select Words, because I am not a native speaker”.
I’m sure he wasn’t alone. Thank you all for persevering through it though!

In case you don’t know, original Select Words are done in Japanese. I know enough Katakanas to do some if any of the puzzles used English-derived Japanese words. Thomas Powell who almost won Nikoli Hurdles 2 said: “Thanks for not doing the Select Words in Japanese :D”. Now wouldn’t that be a fun exercise?

Select Words appear individually in Nikoli Puzzle Communication magazines. I thought about how I could present several puzzles and still have only one answer key. The idea of linking them up suggested itself. I have 3 puzzles that feed their answers to the 4th puzzle.

The smallest puzzle using 5-letter words were all instruments. The 6-letter puzzle used zodiac star signs. My choice was limited and a couple of words have similar patterns so no matter how hard I tried to anagram them, the solutions seemed all too clear. The 7-letter puzzle used animals with nothing obvious in common apart from all having 4 legs. I originally had DOLPHIN and OCTOPUS then stared at the ceiling for too long to come up with anymore sea creatures that were better than ANEMONE.

The final puzzle entries were 5-letter countries. The shaded letters can be scrambled to spell out ITALY, which was the final answer.

Puzzles from Nikoli Hurdles 2 can be found here

Solutions to Nikoli Hurdles 2 – Part 2/5


Puzzle 3: LITS
You may or may not notice the four crosses I laid near the centre of the grid as a start when making this LITS. It is similar to the idea of the Country Road in the last Nikoli Hurdles. There are a few five-cell regions in this puzzle which should give solvers sufficient toeholds to complete the puzzle.

I wanted to make a 10×10 grid but it didn’t work out. I caught a lucky break when the 11-cell region at the upper right had only one possible solution. After tweaking the puzzle for a few minutes, I called it a day and immediately wall off the right hand side of the grid. The result was not too bad right?


Puzzle 4: Slitherlink
The other winner at the Reader’s Choice poll was Slitherlink. Among the most-common puzzle types, this type has to be my worst. I can’t solve Slitherlink, or any variants of Fences for that matter, even if my life depended on it. I tried practicing, I purchased a whole book of Slitherlink, I timed myself and I just never seem to enjoy Slitherlink. This applies to Turning Fences, Polygraph and any other variants (Liar, Pentomino etcetera) that originate from it. I choke when I see dotty grids in any instruction booklets. European puzzle makers are notorious for making Slitherlinks.

No matter how much I dislike it, if the readers prefer so, I shall deliver. My Slitherlink has very little obvious steps; there are no 3s next to 0s, no adjacent 3s, no two 1s in a corner and so forth. The borders should solve quite easily and linking the middle portion of the grid was all there was to the puzzle. Quick intuition is always faster than solving Slitherlink logically anyway, so I suspect most of you did that. A flick through my puzzle shed revealed that this was my very first (!) classic Slitherlink. This puzzle won’t be seeing any of its relative for a while.

Puzzles from Nikoli Hurdles 2 can be found here.

Solutions to Nikoli Hurdles 2 – Part 1/5

Puzzle 1: Masyu

Last year I conducted a poll asking for favourite Nikoli types. Masyu and Slitherlink were the two winners and became the Reader’s Choice for this edition of Nikoli Hurdles.

I quickly whipped up a 10×10 easy Masyu for Puzzle 1. The puzzle looked so boring that I decided to inject a bit more life into it. I aimed for a complete set of pentomino pieces in the givens but the grid was too big for uniqueness. I had to add more pieces and a few circles to get a valid puzzle.


A straight-forward solve to start the first 100m of the track


Puzzle 2: Yajilin
I picked one puzzle from the last Nikoli Hurdles to feature here and it was a Yajilin. An error posed a problem for early solvers when I had a 3 mistyped as a 2. Funnily, Prasanna who ran into the error; correctly assumed I had a typo and just tweaked the puzzle himself!

He continued the track without me even fixing it in time. About the solving, I thought it was a nice Yajilin with clue symmetry. Grandmaster Puzzles recommend using unclued grey boxes in Yajilins in which I can’t say I agree to. Those remind me of “cheater black squares” in American crossword puzzles. They’re there to make the author’s life easier while preserving the puzzle, which I don’t think is a pretty thing to do.

A fairly difficult solve as solver Ivan Koswara vaguely remembered: “I think I recall the Yajilin being extremely tough or something.”

Full PDF of Nikoli Hurdles 2: here